Telegraph system



w. M. BACON 2,376,111

TELEGRAPH SYSTEM 1 942 6 Sheets-Sheet l FiledAug. 26,

May 15, 1945.

May 15, 1945. W. M. BACON TELEGRAPH SYSTEM Filed Aug. 26, 1942 6Sheets-Sheet n .SE if 1 ,/NVENTOR W M. BA CON 9W/@iw A T TOR/VE Y FiledAug. 26, 1942 6 Sheets-Sheet 3 May 15, 1945. w. M. BACON TELEGRAPHSYSTEM Filed Aug. 26, 1942 e sheets-sheet 4 A T TOP/VE)l w. M; BACONTELEGRAPH SYSTEM May 15, 1945.

Filed Aug. 26, 1 942 6 Sheets-Sheet 5 /N VE N TOR n4 M. BA co/v A TTORNEY May'15, 1945. w. M. BACON TELEGRAPH SYSTEM Filed Aug. 26, 1942 6Sheets-Sheet 6 /NVENTOR' M By WMBAcO/v l ATTORNEY Patented May 15, 1945f TELEGRAPH SYSTEM Walter M. Bacon, NewYork, N. Y., assigner to BellTelephone Laboratories, Incorporated, New York, N, Y., a corporationoiNew York f ApplicationlAugust-ZS, 1942,- Serial No. 45.6,-148

6 Claims.

This invention relates toH telegraphreceiving and recording apparatusand more. particularly totelegm form of stationery through y two ormorel advancingme recording equipment or i positions throughv telegraphapparatus..

More specifically,

vention, a tape or Vstationary as disclosedinan entitled Web cont456,206, led on thesarne cooperation ployed ,in

states patent applic signal for attracting the attention of the main.

tenance force and trouble to Ytest busy soT may be directed to this ymaaph recording appa ratus in which some or recording .medium passes theapplication of T, rolled ation of Branson. et v 27, 1 942, So that iscorrected, In addition,n when Ithese are actuated'the tran`s equipment`in trouble is stopped an alarm o r indicatori one,of the transmitequipment in trouble.

, When the contacts are provid dition, the work of attendantsisalso rtothe 'fattvention orA also ment' inmune @einem to control the switchingAequipment educed` because the troubiefof this paiiicuia'typeis atqon yM the operatingv personnel and:

eating 'bothtthe presence and location of ble within the system.

Furi'hermire, by

stopping the tr chanisms f or in accordance;withl this in controlcontact, such L. Corwin, indicator, Serial No. date herewith, is ern--with receiving. equipment and switching circuits disclosed in theUnitedv al., Serial .upon the y or tape to be properly positions, therecord con' disclosed in said Corwin. larm Vor otherr also ',causes themachine. inv

that no further messages chine until lthe trouble I contacts mittertransmitting tolthe d an additional is actuated 'to indicate which" terswas transmitting to they ed and connected.

.as described, lost and 'required to be bly reduced andimade broughtbecause the particular machine and equipe indicated, .thus indi- .thetrouansmitter tol `the" eqiiiprnent in trouble it is possible for ythemessage mission to be :read

mitter and properly tra then in progresser; transrecording instrumentwithout'.requiring to befretransrnitted from the station of `origin and,thus without orth fullherein. lithe rules of. their.`

nsmitted; to Y the"- 'proper the Ines-'-v the loss vof 'the'V message ashas been entailed' heretofore. The disclosuresof the foregoing `patentauoplicationsv ar 'e by 'referencevtot e; hereby incorhe4 same extentcmentor ice, applicant hasnot repeatedthe disclosure of systemsof thetype disclosed in said Branson. etal.

application, aswell `as: in similar systems.,

Thus, kin accordance with theV present invention, the samecontacts;orswitchingydevice arev actuated/in the same manner invresponse to both .a reduction in quantity of tape between two `iixedpoints inithe. system .por mechanism, and falso :to-

an excess of'tape betweenthe twoor more vpoints andthese contactscontrolthe switching circuits in a such a manner that the recording instrumentin'trouble is made busy, the. transmission i-,o it stopped andalarmandxindicating, devices actuated ior indicating both the type ofztroubleand locating the equipment subjected to the trouble.

The foregoing objects and features of this ,invention maybe morereadily, 'understood by referenceto the drawings which illustrate'thetypical embodiment of this invention' incorporating the specific contactarrangement 'disclosed in said applicationof Corwin led herewithasapplied tothe specic telegraph system described in detail in saidapplication-vof' Branson et al., Serial No.448,878, Juneg27', 1942. i Itis `understood that this invention isr not-'limitedto thespecicembodiment set forth hereinl norto the specific type of switching systemdisclosedin said Bransonv et al. application but it may take other formsand be applied to other typesof stationery or record employing devicesaswill bereadily understood by those skilled-in the art. Thenovelfeatures of this invention are specifically set forthin the`claimsappended hereto.

j orsaid switchingvsystem described iny said Bran Referring to thedrawings,

Fig. 1A ,i1lustrat es themanner in--whichv Figs. 2, 3 'and l arearrangedadjacent each other to` show in outline form. the.y variousr circuitsand equipment described intheY patent. applicationv of Bransonet al.referred to. hereinbefore;

Fig; 1B shows themannerin which Figs. 5 and '6 are placedl adjacenteachy other to illustrate.A

in the'system, suchv as set, forthvin the above-A typical tactarrangementits, mode oi Qplzaionas employed in this invention incooperation With switching circuits, such as described in said patentapplication of Branson et a1.

The features of the structure of this contact which appear to be novel,but not claimedl here-L.j

in, are set forth and claimed imrtheabove?vll identined application cfCorwiniiledjinder even date herewith. The featuresf;4 .theswitching .l

equipment which may be novelbut not claimed herein are set forth andclaimed in said aboveidentied application of Branson et al.

Corresponding parts of the apparatus and circuits are designated by thesame characters. in an effortto facilitate the vunderstai-'ldingof@this` in.4 vention.

Considering nrst the mechanical. features of the switching or contactarrangement shown .in

. Figs. '7.- through. 9, and more particularly Fig. 7;;

t4: represents an extension ofthe switching apparatusA or contactdevice. represented hereinv by. atransferV contact arrangement, that is,a contact provided: with both a make and. breakcon.` tact. With thecontact memberl4: at its normal position, the break: contacts. arevmaintained closed, while the make contacts areopen'.

Iny order to actuate the contacts', the contact.

controlmember IIJ is rotated ina clockwisedirece tion as viewed in Fig.`'7'.A Thel end: |3101?. they conf.

trollever.. iiD .will then move member i4; down.- ward, open the breakcontacts and: close the make. contacts.

Control member vI il. is supported bye pivotdll;

free to rotate under control of the. tapeZ. The control member l!! is.provided with an offset por.

tion .|.I which rests upon orabove the tapeandv an extension, armi lf2whichfalsocooperates with tape 2i! as will be described hereinafter. As.pointed: out above. extension lf3 of control mem?. ber I'D rcooperateswith -the contact actuating member I4. The member |4is preferably made.V

of insulating material and attached to a vmov-V able` member of the*contacts orl switching ap. paratus'to be controlled.

As shown in Figs. 8, 9..'and 10, this control de` vice) is attached toprinting reperfora-tor ofthe type disclosed in theabove-.identiiiedAcopending application of Branson et al. said copendingapplication, thetape or stationery 2i!! passes through a feedhole punch. mechanismV 38having a feedhole punch block 3I and a feeding mechanism 32. The tape`then passes over guides'35 and 36 to a printing an'df code 'perforationapparatus shown generally at 38. The printing position'is illustrated at33and the code perforation punchblock indicated by reference numeral'31. A'second tape feeding mechanism 34 is employed to advance thev tapethrough the printing and "code per-forating positions in therecordinginstrument.

The control member H3 is mounted uponrth'e base of this instrument insuch'amanner lthat both the offset portion Il or cont-rol member IU andAextension IZfrest on or above the tape.

As shown inliig'. 8, the control` member il) and the tape 2l! are sho'wnhin the normal Aposi-t-iion with lthe extension i2 offcon'tro'lmember H] restingA upon guide 33. Generally'the extension i2 of' AsvdisclosedA in 40 this occurs the tape will Ibulgel and form a loop.

the control member rests upon vthis guide with the paper or tape 2Bbetween the extension I2 and guide 3B.

It sometimes happens that for some reason or other, one or the other ofthe feed mechanisms fails to properly advance the tape 2li through therecording mechanism so that the supply of tapeI 2t. between the feedhpleperforating mechanism Pilland the messagerecording mechanism 38 eitherbecomes reduced below a predetermined minimum or else exceeds somepredetermined maximum quantity.

It the supply of tape 20 is interfered with, the feed me,chanismN 3.2will generally tear the tape betweenpthejieedholes. This will interferewith the norm advancing of the tape through the feedholeperforatingmechanism 3l and inasmuch as the feed mechanism 3d will continue tooperatenormally for a short interval of time, the supply of tape betweenthe feed punch block 3i and the code punchlbloclc 31 will; he reduced.This condition is shown in Fig. 9. The reduction of tape between thesetwo- DoSitOIls in the machine will` cause the controlmember i0. to.

rotate in a clockwiseA direction abfout pivot t3 due to the tapeengaging; the onsetl portion il of control member It and liftingthisportion.` The rotation of member It),y in va clockwisev directionwill causev the extension |73 to engage. the contact actuating member i4and actuate the switching apparatus to cause the contactsy to open orclose, or both, as shown in Fig. 'L

If thetape 20 [becomesstuck inpassingthrough thel recording orperforming apparatus` it instead of prior. to or during the passagethrough. the perforating mechanism 3D, asdescribed above, anexcess ,oftape willV accumulate between. the feedhole perforating mechanism andthe message recording mechanism asshownin l0. When duev to the actionlof member le andA guides 3,5. and 3,6 as shown at 2|` due to the actie-nof. the guide members 35 and 3,6'. 'lhek bulge 2! will` en,- gag'e theextension l2 of the control. member it and again rotate this member in aclockwise direction and cause the contacts. controlled Aby member 1 4 tobe actuatedin the same manner aswhen the supply of-L tape between. thefeedhole punch position and the recording position was reduced to apredetermined minimum quam, tity- Thus the contacts; controlled bymember it are actuated in the, same manner both by reductionlin thenormal amount of tape betweenJ these. two points and by an excess oftape Vbetween them.

In accordance with the present invention, this contact is incorporatedin a switching system described in said above-identied application ofBranson et al., which switching system is shown in outline form in Figs.2, 3 and 4 when posi.

tioned as shown in Fig. 1A.

Briefly, the system comprises a plurality of party lines 2H) and-'260.ThesepartyY lines comprise 'receiving channels 2H and 26| respectively,for` the transmission of signals` from a cen.- tr-al switching centershow-n in Figs. 3 and 4 to the respective stations served by these partylines. The party lines also `include, transmission channels 2I2 and 262respectively. for the transmis-r sion of 4signals and from the,outlying" stations to the central switching center. As described in theabove-identified application of Branson et al., these party lines may bearranged to operate either on a full duplex or half duplex basis.' Theparty line 2| IJl is assumed to be a full duplex party line, while theline 260 is assumed to be a half duplex party line.A As will be wellunderstood by those skilledfin the art, any number of fullduplex andhalf duplex lines may be provided. As shown in the drawings, full duplexparty line 2li] extends to the secondary switch 'includes a channel 29|for ytransmitting messages `from the switching center shown in Figs. 3andfi to the second switching center 293 where receiving equipment294'is associated therewith. The trunk 290 also includes a secondchannel 292 for transmission of signals `from the sending equipment 295at the second switching center 293 to the central exchange shown inFigs.- 3 and 4.

The party lines 210 and 260, as well as the trunk, circuit 290, mayincludev any suitable type of telegraph transmission channel. As shownin the drawings, these lines are shown as two oneway full metallictransmission paths in an eiort to avoid further complication of thedisclosure. It is to be understood, however, that these transmissionpaths may include one or more of the following types of telegraphtransmission, systems and in actual practice will usually combine anumber of the different following types of s transmission paths and aswill be readily understood by those skilled in the art,r thetransmission paths ofthe different lines willvary from section tosection independent of the type of transmission apparatus employed inany of the other lines or trunk circuits or sections.

Brieiiy,` these lines and channelsmay include both full and half duplexlow frequency telegraph lines or channels which may be operated either4'.'

on a ground return or full metallic basis and which channelsmay comprisetelegraph channels of composited telephone and telegraph lines of any ofthe well-known composite systems including simplex and phantom circuitsas well as so-called Morse legs of cable quads. These channels may alsoinclude channels of the sor-called time division multiplex telegraphsystems for the transmission of signals in either one or bothdirections.

' The telegraph transmission channels may also include channels of voicefrequency carrier telegraph systems as-well as channels of highfrequency carrier current telegraph systems and also radiochannels.

These party lines may also include the usual types of terminal andinterconnecting equipment for the various types of communication systemset al. application, the party lines terminate at the central exchange inequipment individual to each of the lines. The incoming channel partyline 2|2 terminates in an incoming line circuit 322. The incoming 'linecircuit causes the message to be recorded either by receiving onlyteletypewriter 323 when the messages are intended for the centralswitching station or upon a combined reperiorator and transmitter 324comprising reperforatingl unit 326 and a transmitting unit 325. Thetransmitter 325 is associated with the director circuit 321 whichcontrols a crossbar or other type of switch including the selectormagnet 328 and the holding magnets420 and causes the transmitter to beconnected to some channel extending towards the party-line for which themessage is intended.

As described in the said Branson et al. application, each message ispreceded by a pluralityLk of address characters, which characterscontrol the y directing circuit 321 and cause transmitter 325transmission through the crossbar switch.l The party line 210 isprovided with two sets of channels and each channel provided with agroupof lrelays individual thereto illustrated symbolically at` 320 and 32|.rEach of the channels is also provided with combined reperforating andtransmitting instruments 3M and 315. The transmitting units of theseinstruments are arranged to transmit' alternately over the receivingchannel of the party line 210 and are provided with various controlrelays 3| I, SI2 and 3l3. A transmitter start circuit 3l is alsoassociated with the receiving channel or party line 2 I0 fortransmitting transmitter start signals orcontrol patterns over thischannel. These transmitter start patterns control the switchingequipment at the secondary switching center and cause theA associatedtransmitters to be started into operation when they are supplied withstored message material available for transmission.

The secondary switching centers alsores'pond to at least certain of theaddress characters and cause thereceiving equipment controlled by themto be selectively and operatively connected to the receiving channel ofthe party line in accordance with address characters so that therespective receiving equipmentsv will receive the message intended forthem.

The other'party lines of the trunk circuits are similarly equipped withthe various circuits as described above. In the case of the half duplexlines only one channel through the crossbar switch will generally beprovided since half duplex lines will only be provided when trahie or`messages for the stations and lines connected thereto are not heavy. Notransmitter start circuit 'has been shown for the trunk circuit becausesuch a circuit generally will be unnecessary since there will be notransmitters to be started under control of the central switchingcenter. With these exceptions, the equipment provided for each of thelines and trunks operates in substantially the same manner and performssubstantially the same function.

Message originating equipment comprising monitoring teletypewriters Mil,keyboard perforators lill, transmitterstlZ, control relays 4| 3 anddirector circuit M4 is provided at the central switching station for thetransmission of together with a director circuit 423, are provided forthe reception of certain messages intended for'stations which it isdesired, for one reason or another, to lintercept and preventtransmission to their'ultimate station ofv destination at the particularmoment.

The operation of the circuits of sucha typical switching system has beendescribed in greater detailv in the above-identified Branson et a1application and need not be repeated here. It is to be uiderstood,however, that equipment and circuits of this invention cooperate with`circuits-oi said Branson `et, al application as will be describedhereinafter.

More specically, in accordance with the present invention, thereperforating devices 353-, SIB, 325, 338 and 42|, as well as the otherreperforating devices employed in this system including reperforatingequipment associated with the trunk 296, maybe provided with the tapecontrolled contacts and control circuits in accordance with thisinvention. The manner in which these contacts control the switchingcircuits may be more readily understood by reference to Figs. 5 and 6.Here contacts I4 are controlledvby the control member II] of thereperforator 505. Contacts I4 cooperate with other contacts of thereperforator 506 and control relays and circuits, Fig. 6, as will bedescribed hereinafter.

Specifically, Figs. 5 and 6 are identical with Figs. 45 and 46 of theabove-identiiied application of Branson et al. except that therepresentation within the box 596 designating the reperforator has beenslightly alteredl in order to provide suiiicient space for showingcontacts I4 and connecting them in series with the armature of theuniversal contacts 540. Figs. 5 and 6 of the drawings appended hereto,could, therefore, be substituted, without change, for Figs. 45 and 46 ofsaid Branson et al. application.

Fig. 5 could likewise be substituted for Figs. 19, 20, 62 and 63 or"said Branson et al. application without any change other` thanrearranging the leads and connections to the other iigures so that theequipment as shown in Fig. 5 would cooperate with the circuits adjacentto these other figures. In other words, contacts I4 can be connected inseries with the armature of the universal contacts of the reperforatorsshown in these gures. In addition, contacts i4 may also be connected inseries with the armature of the universal contacts of the reperforatorsshown in Figs. 82 and 87 and in each case where these con-- tacts areconnected in series with the armature of the universal contacts of thereperforators in Figs. 19, 20, 45, 62, 63, 82 and 87, the circuitandsystem of said application will function substantially as described insaid application, except as modified by the description herein.

Contacts I4, as described herein, may also be connected in series withthe armature of the universal contacts in the reperforators shown in areconnected in series with the armature of the universal contacts of thislatter group of reperforators, they merely cause an indicator and alarmto be actuated ina manner similar to the manner described hereinafterbut do not make the reperforating equipment busy nor do they stoptransmission as is the case with the i'irst group of reperforatorsenumerated above.

As will be readily understood by those skilled in the art, contacts I4may be provided in series with the armature of universal contacts ofeither group of reperforators enumerated above without being provided-for the other group, or they may be provided for both groups. Inaddition, it is not essential that these contacts be provided for eachperforator of either group. For those perforators for which the contactis not provided, the operation will be as described in the aboveidentiedapplication of Branson et al., whereas.

for each reperforator for which contacts are provided, the operationwill be as described in said Branson et al. application as modified bythe description herein. v

Turning now to the operation of the circuits as shown in Figs. 5 and 6,which is similar to the operation of the corresponding contacts whichare provided for any other reperforator of the first group enumeratedabove, when the reperforator is idle, relays GIG, 6I I, SI2, EIB, Silland 623 are released. Relays i522 and 621i are operated as shown inthe-drawings. Relay 524 is operated in a circuit extending from batterythrough its winding, to ground to the lower break contacts of relay SI2.Relay 522 is maintained operated in a circuit extending from batterythrough its winding to ground, through the lower operated contacts ofrelay 624.

When the reperforator 585 is seized under control of an address code, asdescribed in said above-identified application of Branson et al., relay6I3 will be operated. A little later relay 6 I4 is operated and thenrelay 6I3 released.. Upon the release of relay 6I3, a circuit will becornpleted for the operation of relay 6I2. The operation of relay 6I2completes a circuit for the operation of relay 6 I I from battery,through the winding ofrelay GII to ground, through the lower inneroperated contacts of relay SI2. Relay 6I I, in operating, connectsground to lead SIS and thusl makes reperforator 505 busy and prevents itfrom being seized by any of the other switching equipment.

A short time interval after relay SI2 operates, under normal operationof the system, signals will be transmitted to the reperfo-rator 556. Theoperation of relay GIZ, as described above, interrupts the operating.circuit of relay 624, which relay in releasing, interrupts the operatingcircuit of relay 622. Relays 624 and 622 are slow release relays` andmaintain their armature operated for an appreciable interval of timeafter the circuit through their windings is interrupted. Consequently,under normal operation of the sys- V tem, signals will be received bythe reperforator 502 prior .to the release of relay 622. Ir" no signalsare received by reperforator 5GB or this' reperforator does not respondto the signals due to some troublecondition, relay 622 will release andcomplete a circuit for the operation of relay Sie as describedhereinafter. Relay 622, in releasing, will also short-circuit resistance628. This mode of operation of the circuit has been described in detailin said. above-identified application of Branson et al. and need not berepeated. in greater detail here.

If for any reason contacts I4 are open at the time reperforator 506 isseized,lthe circuits-will respond in the same manner aszindicatedabovewhen no signals are received or the reperforator 506 does not respondtothem; f f

Assume now that.signalsarefreceved during the release time ofrelaysi622and 624, .that contacts I4 are closed, andlthatthereperforator 50u' responds by the received signalsJ-.During the responseof the reperforator 506 to any 4code combination, the universallcontacts '1540 are lmomentarily operated and complete a vcircuit forthel operation of relay 623 from battery, through the Vwinding of relayy623, the Vuppers. inner'operated contacts of relay 62|to'groundthroughthe momentarily operated universal contacts 540.and the closed contactsI4. 1 L

`Relay 623 in operating, completes acircuitfor maintaining itselfoperated from battery, through its Winding and the lupper inner operatedcontacts of relay 62| to ground, through the upper operated contacts ofrelay 623. The operation of relay 622 also completes a circuit formaintaining relay 622 operated from battery, through the winding ofrelay 622 and the lower operated contacts or relay 623, through thenormal contacts of the universal contacts 540 to ground through closedcontacts I4. During the normal operation of the reperforator 506, theuniversal contacts 540 will be in their normal or unoperated position asufficiently long interval of time during or following the reception ofeach code co-mbination to maintain the slow-release relay 622 operated.Consequently, relay 6IIJ will not be operated and resistance 628 willnot be short-circuited.

If for any reason contacts 540 are not operated during the releasingtime of relays 624 and 622, relay 622 in releasing, causes the operationof relay 6I0 in a circuit extending from battery through its winding andthe upper break contacts of relay 622 to ground, through the lower outeroperated contacts of relay 6I2. Relay 6I0 in operating, completes anobvious circuit for lighting the tape-out lamp 533, connects ground toalarm lead 638 for actuating an alarm and also connects ground to leadBIS, thus maintaining the reperforator 506 busy and preventing it frombeing seized by any other of the switching equipment. t

The release of relay 622 also short-circuits resistance- 628 and stopsthe transmission of signals to the reperforator 506 and actuates alarmdevices and the indicator 350 associated with the transmitter thentransmitting to reperforator 506 so that not only may the reperforator506 be readily located by the maintenance force, but

also a transmitter connected thereto so that any trouble which may havedeveloped in the transmitter connected to the reperforator 506 may beYreadily located.

circuits respond in the same manner as if reperforator 506 did notreceive signals or failed to respond to the signals transmitted to it.`

If contacts I4 open during the transmission of a message to thereperforator 506, they interrupt the holding circuit described above forrelay 622, which relay will then release and complete a circuit for theoperation of relay BIO, as described above, and also short-circuitresistance 628.

-reperforator. 506 is in trouble.

With resistance 628 short-circuited, the-transmissionfrom'thetransmitter transmitting to the reperforator 5061s interrupted.RelayA 6I0 in operating, connects gro-und tothe alarm lead 63B and tothe busy ortest lead BIS. Relay 6I0 in operating, also ycompletes'anobvious circuit for lighting lamp 533, thus indicatlng the particularThereafter, the operator or attendant may determine the cause or thetrouble and if one o-r the other of the tape advancing mechanisms isfunctioning improperly the operator or attendant will either replacethemachine or' correct the trouble; then by properly operating keys, `as.described in the Vabove-identiiied application of Bransoncet -:al.,theoperator may restore the circuit toits normal oridle condition. Theattendant may alsov remove ar portion of Vthe message from the.,tapeinthe reper- 'orator 506 and reset the tape` in the transmittertransmittingto this,reperforatorsothat a complete message will beperforated in the tape by reperforator 506 for later transmission to theproper subscribers station, as described in said Branson et al.application.

Thus, the operation of contacts I4, due to improper operation of eitherof the tape advancing mechanisms of the reperforator 506 causes 1) thelamp 533 to operate to indicate the reperforator in trouble; (2) causesan alarm to be actuated to attract the attention of the operator ormaintenance people; (3) connects ground tothe busy test lead and makesthe reperforator test busy so that it will not be seized by any other of,the switching equipment so long as the trouble condition remains, and(4) stops the operation of the transmitter transmitting to thereperforatorv 506 and actuates indicators and other alarms to attractthe attention of tne maintenance people and indicate the particulartransmitter transmitting to reperforator 506.

What is claimed is:

l. In a'telegraph switching system, a recording instrument, a supply ofstationary therefor, means for advancing said stationary through saidinstrument, switching apparatus for automatically selecting andestablishing a transmission path to said instrument under control ofreceived signals, busy indicating apparatus for said instrument, andmeans responsive to improper operation of said stationary advancingmeans for interrupting transmission over said established path andmaking said instrument, test busy to prevent selection thereof by saidswitching apparatus. 4

2. In a switching system, a telegraph reperforator for perforating atape in accordance with received telegraph signals, apparatus for ad#vancing said tape through said reperforator past two fixed pointstherein, and apparatus controlled bythe amount of tape between said twopoints for making said reperforator busy and preventing transmission ofsignals to it.

3. In aA telegraph recording instrument, appa,- ratus for advancing arecording medium past two points in said recording instrument, aswitching device operated in the same manner by an increase and adecrease in the recording medium between said two points, switchingequipment for directing messages to said recorder, and apparatusrresponsive `to the operation of said switching device for preventingsaid switching equipment from directing further messages to saidrecorder.

4. In a telegraph recording instrument, apparatus for advancing arecording medium past two points in said recording instrument, aswitching device operated in the same manner by an increase and adecrease in the recording medium between said two points, switchingequipment for directing messages to said recorder, and apparatusresponsive to the operation of said switch ing device forpreventing saidswitching equipment from directing further messages to said re corder,indicating apparatus indicating both the recording instrument in whichthe record medium is not properly advanced therethrough and the -originof the message which is then being transmitted. Y

5. In a telegraph switching systemva signal recorder, switchingapparatus automatically controlled by telegraph signals for selectingsaid recorder under control of predetermined -telegraph signals,apparatus for advancing a recording medium through said recorder inresponse to reception of signals thereby,and apparatus responsive to theimproper operation cf saidadvancing apparatus for preventing theselection o f said recorder by said switching apparatus.

WALTER vM. BACON.

